<!DOCTYPE html>
<html lang='en'>
<head>
<meta charset='UTF-8'>
<meta name='viewport' content='width=device-width, initial-scale=1.0'>
<title>Document</title>
</head>
<body>

  <div id='app'>
    <input type="text" v-focus="10">
  </div>

<script src='https://cdn.bootcdn.net/ajax/libs/vue/2.6.12/vue.js'></script>
<script>
  Vue.directive('focus', {
    inserted(el, binding) {
      // console.log(el);
      // console.log(binding);
      el.focus();
      // el.style.background="red";
    }
  })

  const app = new Vue({
    el: '#app'
    ,data: {
      msg: 'Hello Vue'
    }
    ,methods: {

    }
  })
</script>
</body>
</html>